Optical inspection systems such as automated bulk processing systems are used for determining optical characteristics of articles. The optical characteristics may be determined at a wavelength visible to the human eye or at a wavelength not visible to the human eye. Optical inspection systems can perform a variety of tasks such as inspecting or sorting bulk articles including raw or processed fruit, vegetables, wood chips, recycled plastics, and other similar products. The systems can rapidly separate very large quantities of articles into different categories.
The articles are placed on a conveyor belt and moved by the conveyor belt past an inspection station, which inspects the articles for optically-detectable characteristics such as size, color, or shape. The inspection station sends signals to a sorting or treatment station where the articles are sorted or treated by category based on optical characteristics of the articles detected by the inspection station. One type of treatment is to remove defective or foreign articles from the flow of articles carried by the conveyor.
In a particularly effective method of removing defective or foreign articles, the conveyor belt moves rapidly, supporting the flow of articles on its upper surface, in one direction toward a turning bar. At the turning bar the conveyor belt turns sharply downward to return in an endless loop to other parts of the system. Where the conveyor belt turns downward, the articles continue to move forward in the direction in which the conveyor belt had been conveying them; thus, the articles are projected from the point where the conveyor belt turns and travel through the air following an approximately ballistic trajectory. The treatment station is located in a treatment region through which the articles travel. While a defective or foreign article is travelling through the treatment region, the treatment station directs an accurately timed blast of a fluid, such as water or compressed air, at that article. The blast of fluid directs that article out of the trajectory followed by acceptable articles and toward a rejection bin or other suitable means for collecting it. Acceptable articles are not struck by a blast of fluid and continue on their trajectory toward a bin or other suitable means for collecting them.
FIG. 1 is a fragmentary, partly sectional, and partly schematic elevation view of part of an optical inspection system or automated bulk processing system 10 designed for sorting articles 12 such as whole potatoes. Articles 12 travel in a direction 14 on an outer surface 16 of a conveyor belt 18 until the inner surface 20 of conveyor belt 18 contacts a turning surface 22T of a turning element 22. At or near that point, conveyor belt 18 turns sharply away from articles 12 to run back as an endless loop to other parts of the system. Articles 12 continue to move and travel on an initial trajectory 24 through a desired region 26. Conveyor belt 18 is supported over most of its length by a support sheet 28 and is driven by a drive roller (not shown) that pulls conveyor belt 18 over and away from turning element 22. Support sheet 28 has a gently dimpled (not shown) surface 28S that contacts surface 20.
Articles 12 are optically inspected at an inspection region 30 while travelling past an inspection station or stations 32 located either above surface 20 or above and/or below trajectory 24 in region 26. At inspection station 32, articles 12 are illuminated so that cameras or other optical detection devices at inspection station 32 can view the illuminated articles 12 and a logic unit or controller can determine characteristics of articles 12 based on the optical information. Commands based on the optical inspection are sent by a control unit to a treatment station 34 in a treatment region 36, where selected articles 12 are treated, e.g., removed from the stream of acceptable articles (as shown) or cut or otherwise processed. To remove unacceptable articles, for example, a blast 38 of a fluid such as compressed air or water is directed at foreign or defective articles 12S while they are moving through treatment region 36. Blast 38 impels foreign or defective articles 12S to follow a rejection trajectory 40 away from a trajectory 42 (which is typically a continuation of initial trajectory 24) followed by acceptable articles 12U.
The effectiveness of bulk processing systems such as system 10 is affected by the extent to which initial trajectory 24 is predictable. To achieve greater predictability of initial trajectory 24, turning element 22 has a turning surface 22T that allows conveyor belt 18 to move down from articles 12 in a short distance and thus that allows a high radial acceleration of surface 16 away from articles 12. Turning surface 22T thus has a relatively small radius of curvature. It would be difficult to support a small-radius rotating turning element such as a roller over the width of conveyor belt 18 while avoiding unacceptable flexing of such a roller. Thus, turning element 22 is generally provided as a rounded, fixed, non-rotating turning bar or nose bar or bullnose rather than a roller. Turning element or turning bar 22 is supported against the force exerted on it by conveyor belt 18 by a support bar 23 extending along the length of turning bar 22.
Conveyor belt 18 typically moves at such a high speed (for example, 500 feet (approximately 152 meters) per minute) that substantial heat can be generated by friction between inner surface 20 of conveyor belt 18 and turning surface 22T. To reduce the friction between those two surfaces, to dissipate some of the heat generated by the friction, and to reduce wear on those two surfaces, a lubricant such as water is conventionally applied to those surfaces where they meet.
FIG. 1 shows a conventional method of applying the lubricant. A spray pipe 44 extends across the width of conveyor belt 18 and parallels a region 46 where inner surface 20 meets turning surface 22T and where conveyor belt 18 thus turns around turning bar 22. Pipe 44 has holes bored in it, or nozzles attached to it, that direct a spray 48 of pressurized water into region 46. Some of the resulting water adheres to and lubricates surfaces 20 and/or 22T, but most of it drips or flows away from region 46 as wasted water 50 or sprays out from system 10 and thus also is wasted. Most of wasted water 50 is carried away from turning bar 22 on surface 20 as conveyor belt 18 moves through system 10. As a result, much more water falls around and below turning bar 22 and in other areas to which surface 20 carries it than was actually needed to lubricate surfaces 20 and 22T.
The spray system has serious disadvantages. Spray 48 ordinarily does not uniformly coat inner surface 20 where it meets turning surface 22T. This causes an uneven reduction in friction, an uneven degree of cooling, and an uneven reduction of wear across the width of conveyor belt 18 on surface 20. As a result, conveyor belt 18 experiences uneven thermal stress and/or wear and may break sooner than if it had received the lubricating water uniformly. The spray system also wastes water, which must be not only supplied to the spray system but also removed from the vicinity of the inspection system.
There is thus a need for a lubricating system for region 46 that will apply a lubricant such as water uniformly across the width of surfaces 20 and 22T and that requires less water throughput than the spray system.